Apparatus for producing sized ferroalloy particles

ABSTRACT

A process and apparatus for disintegrating a stream of molten ferroalloy into solidified spheroidal to spherical configurations for use as additives in metal producing furnace operations or the like.

United States Patent [191 Young et a1.

APPARATUS FOR PRODUCING SIZED FERROALLOY PARTICLES Inventors: ClaudeFrank Young; Charles Martin Offenhauer, both of Niagara Falls. NY.

Assignee: Union Carbide Corporation, New

York. N.Y.

Filed: Jan. 19, 1972 Appl. No.: 219,099

Related US. Application Data Division of Ser. No. 28.594, April 15.1970. Pat. No. 3.660544.

US. Cl 425/8, 264/8, 65/15,

65/21 Int. Cl. B29c 23/00 Field of Search 425/8, 332, 402; 264/8;

[ Mar. 19, 1974 [56] 7 References Cited UNITED STATES PATENTS 3.174.1823/1965 Duncan 425/8 3.272.893 9/1966 1 Mogensen 264/8 3.358.323 12/1967Chisholm l 425/8 3.532.775 10/1970 Brondyke et al. 264/8 X 1.210.09712/1916 Perry et a1. 425/8 X 2.062.093 11/1936 Kann 425/8 2.439.7724/1948 Gow 425/8 X Primary Examiner-Robert L. Spicer, Jr. Attorney,Agent, or FirmFrederick J. McCarthy, Jr.

ABSTRACT A process and apparatus for disintegrating a stream of moltenferroalloy into solidified spheroidal to spherical configurations foruse as additives in metal producing furnace operations or the like.

6 Claims, 2 Drawing F lgures MOLTEN METAL PATENTEUIAR 1 9 1914 3.797,978

SHEET 2 OF 2 MOLTEN METAL APPARATUS FOR PRODUCING SIZED FERROALLOYPARTICLES This is a division, of application Ser. No. 28,594 now U.S.Pat. No. 3,660,544, filed Apr. 15, 1970.

FIELD OF THE INVENTION This invention relates to a process and apparatusfor producing substantially uniform ferroalloy sizes having a somewhatspheroidal configuration. The process consists in subjecting a moltenmetal to a centrifugal force sufficient to direct and disperse themolten metal into a radially defined zone wherein the dispersed metalparticles contact and roll upon the surface within the zone so that theroll contact action, when added to the surface tension action of themetal, will be sufficient to draw each particle into a somewhatspheriodal to spherical shape. The molten to semi-molten ferroalloyparticles are then discharged from the radial zone and quicklysolidified into their adopted shapes. The ferroalloy particles or shots,so produced are relatively uniform in size, however, the size can varydepending upon the degree of centrifugal force imparted to the moltenmetal and the contour of the radially defined zone.

DESCRIPTION OF THE PRIOR ART Various methods are employed to producesmall finless ferroalloy sizes for use as additives in metal alloyfurnace operations. A uniformly sized ferroalloy charge is required tobe relatively free of fines and fins so that when the charge reaches itsfinal destination it can be fed into a metal producing furnace withoutfear that fines will explode or otherwise hamper the operational mode ofthe furnace.

One method for producing small sized ferroalloy charges is to cast themto the size desired. This method is expensive and still yields endalloys having fins which require another operation to remove. Inaddition, sizes between 8 Tyler mesh up to inch, and preferably V4 inch,are difficult to cast on a large scale basis.

Another method presently used is in casting alloy sizes in large chillsand then crushing the alloy by conventional means to produce variousalloy sizes. Due to the friability of the alloy, a considerable amountof fines and off-size particles are produced which decrease the netoutput quantity of a selected alloy size. Separating the selected sizefrom the off-size elements requires another operation which addsadditional time and expense to the overall production operation.

The disadvantage of present methods in producing an alloy size within asomewhat narrow range is in the large amount of off-size pieces that areco-produced. The present invention provides a method wherein theoff-size pieces are greatly minimized and the selected alloy sizes aresomewhat spheriodal to spherical in configuration. In addition noexpensive crushing, casting or forming operation is required.

SUMMARY OF THE INVENTION Broadly, the process and apparatus of thisinvention comprises subjecting a stream of molten liquid within aninsulated zone to a centrifugal force sufficient to direct and dispersethe molten stream into a radially defined sinuous type passage whereinthe molten to semimolten particles of the dispersed stream contact androll upon at least one curvilinear surface of the passage.

The molten liquid can be any material that solidifies at roomtemperature such as molten metal. The rolling contact action, togetherwith the surface tension action of the molten to semi-molten liquid, issufficient to influence the small particles into adopting a somewhatspheroidal to spherical configuration. Preferably, the molten tosemi-molten particles should roll upon a rotating member having aninclined curvilinear surface and then be tangentially projected to theopposite surface of the passage having a declining curvilinear surfaceso that maximum circumferential contact between the spheroidiallyforming particles and the surfaces of the sinuous type passage can beobtained. To increase this contact action, the opposite surfaces of thepassage may be counter-rotated with respect to each other thussubjecting the spheroidal to spherical particles to an increasedspirally rotating motion, such motion derived from combining the radialmotion due to the centrifugal force and the circular motion due to thecounterrotating surfaces. It is this combination of radially directedcontact force and circular imparted contact force, in addition to therelatively low surface tension force, that shapes the dispersedparticles into spheriodal to spherical configurations.

The molten to semi-molten alloy particles, while still subject to thecombined forces, are ejected from the peripheral outlet of the sinuoustype passage and quickly quenched or solidified in their adoptedspheroidal to spherical shapes. A receptacle or the like containing aquenching medium may be employed to catch and solidify the alloy shapes,such shapes being somewhat spheroidal to spherical in degree dependingon the centrifugal force, the degree of the shape of the curvilinearsurfaces, the number of peaks of the sinuous passage and the particularviscosity of the molten liquid used. A sinuous passage having at leastone peak is required to insure that the dispersed particles will roll onat least one incline curvilinear surface thus providing sufficientcontact force which can be added to the surface tension force toappropriately shape the particles. The inlet of the sinuous passage canbe made adjustable so as to regulate at least the maximum size of thedispersed particles being forced through the passage.

DESCRIPTION OF THE DRAWING The invention will be more readily understoodby reference to the drawing wherein:

FIG. 1 is an elevated sectional view taken through the center of theapparatus of this invention.

FIG. 2 is an isometric view of the rotating anvil of the apparatusshowing the spiral path taken by the dispersed particles.

In FIG. 1 hot molten metal is axially fed upon rotating circular anvil 1which is made from a material that can withstand the high temperature ofthe molten metal, such material being graphite, aluminum, magnesia, castiron or any refractory metal that will not react with the molten metal.The anvil has a conically shaped projection 2, centrally disposed andextending upward. An inclined curvilinear surface 3 extends radiallyoutward from projection 2 and before reaching the peripheral vicinity,the surface assumes a zero slope and then slopes slightly downward. Arotatable drum 4 has an axial opening 5 into which the molten metal isdirected to contact projection 2. The undersurface 12 of drum 4 iscurved with a mating curvilinear surface to that of surface 3 butextends radially outward further so that when axially disposed on top ofanvil l a sinuous type passage 13 is defined. It is also possible tohave anvil I extend further out than the drum so as to terminate thesinuous passage in an upward direction. The drum, like the anvil, can bemade from any material that can withstand a high temperature environmentwithout reacting with the molten metal being disintegrated into smallparticle sizes.

Motor 6 is used to rotate anvil 1 while motor 7 rotates drum 4 in acounter direction. Cone-shaped skirt 8 is used to protect the anvilsrotating means from any misdirected metal particles.

Receptacle 9 may be a simple annular type receptacle or at least twoarcuate receptacles which when juxtaposed will form an overall annularreceptacle. This receptacle, containing a quenching or solidfying medium14, is placed below and radially outward from peripheral outlet 15 ofthe sinuous passage so as to be in a position to catch the exitingspheroids l1.

Cylindrical shell 10, in addition to supporting drum 4, provides aprotection barrier from misdirected alloy particles exiting from thesinuous passage.

In the operational mode, molten metal, such as ferroalloy, is fed intoaperture in drum 4 and directed to contact projection 2. The rate of themetal feed is variable but must be slow enough to allow sufficientcontact with rotating projection 2 so that the metal can becentrifugally projected and dispersed into the sinuous type passage 13between drum 4 and anvil 1. With the anvil rotating, the dispersed metalparticles are forced to roll and slide upon curvilinear surface 3whereon each particle travels in a spiral path as exemplarily shown inFIG. 2. Each particle traveling in this spiral path is subjected to aradially applied centrifugal force A and a circular or rotating force Bwhich is normal to force A and together the forces subject the particleto maximum circumferential contact with surface 3 of revolving anvil l.The molten spheroidally forming particles are then tangentiallyprojected onto the curvilinear undersurface 12 of the drum where theycontinue to roll thus increasing the rolling contact acting thereon. Agreater roll contact between the spheroidally formed particles and thedrum can be obtained by rotating drum 4 in a counter direction to thatof anvil 1.

The somewhat spheroidal to spherical particles 11 are then ejected atperipheral outlet 15 in a downward direction into a receiving receptacle9. A quenching medium of any non-reactive gas or liquid, such as water,oil, molten salt, molten glass or any combination thereof, quicklysolidifies the particles into their adopted shapes. A jet of cold airdisposed in the vicinity between the passage outlet and the receptaclemay also be used to effect solidification of the particles. Ascreen-like net or mesh liner within the receptacle may be employed forfacilitating the removal of the particles. It is also possible to employa revolving type mesh liner which could be used to direct the particlesto a preselected section in the receptacle where a conveyor, inclinedradially outward through a suitable opening in the lower portion of thecylindrical shell, would continuously remove the particles and directthem into a collection container.

Since conical projection 2 continuously contacts the molten metal feedthereby being subject to wear. it may be made replaceable by providing athreaded or geometrically shaped lower portion which can be threaded orinserted into a mating recess in the center of the anvil.

The degree of the curvilinear passage, as to slope and the number ofpeaks, is variable and depends on the degree of sphere required for thesolidified alloy. The peripheral outlet of the passage may terminatewith a positive slope thereby directing the exiting alloy particles inan upward direction.

Molten ferroalloys suitable for use with this apparatus includeferrosilicon, ferromanganese, ferrochrome, ferrochrome silicon,magnesium ferrosilicon, silicomanganese and the like.

EXAMPLE Using an apparatus similar to that shown in the drawing, severalheats of molten 50 percent ferrosilicon, each weighing about 30 pounds,was poured into the central opening of a graphite drum to contact arotating conical protrusion of a graphite anvil. The conical protrusionbroke the stream of ferrosilicon into small particles and dischargedthem into a sinuous passage similar to that shown in the drawing. Theferrosilicon particles were made to spirally roll and slide upon therevolving anvil and then were tangentially projected to contact and rollupon the under curvilinear surface of the drum. The particles under theforce of surface tension and roll contact action were influenced intoadopting a somewhat spheroidal to spherical shape by the time theyreached the peripheral outlet of the passage. They were then dischargedfrom the sinuous passage and caught in a plurality of circularreceptacles positioned below and concentrically outward from the passageoutlet. The receptacles were filled with water which immediatelyquenched the caught ferrosilicon particles into their adopted shapes,such shapes being somewhat spheroidal to spherical in configuration.

The solidified particles were then subjected to a screen analysis testand found to contain 92 percent by weight sized between 8 Tyler mesh andMpjnch.

The term somewhat spheroidal is intended to mean the shape of discreteparticles, such as shots or pellets, which may have protrusionsdisfiguring a true spheroidal shape. These protrusions occur from thesolidification of the particles prior to the particles assuming a truespheroidal to spherical shape. Although the particles depart from a truespheroidal to spherical shape, they are still commercially usable aslong as they fall within a particular size range.

It is to be understood that a higher percentage of uniformly shapedparticles can be obtained by rotating the drum of the apparatus of thisinvention in a counter direction to that of its mating rotating anviland/or by extending the radial length of the sinuous passage so formedby the drum and anvil since either or both of these modifications willincrease the spiral path upon which the particles will roll therebysubjecting the particles to a greater circumferential contact with thesurfaces of the passage. This increased circumferential contact, due tothe increased radial and circular rolling motion imparted to theparticles, will aid in influencing the particles to adopt a morespheroidal shaped configuration.

What is claimed is:

1. An apparatus for disintegrating molten liquids into somewhatspheroidal to spherical configuations comprising a rotatable circulardrum having a centrally located opening through which the liquid canflow; a power driven rotatable circular anvil concentric with andlocated below said drum; said drum and said anvil being rotatable inopposite directions; said anvil having a conically shaped centerprojection directly under the opening in the drum and a curvilinearupper surface extending radially outward from said projection whichmates with and is spaced apart from a similar curvilinear lower surfaceon said drum; said curvilinear surfaces forming a sinuous passage havingat least one peak through which the liquid can be centrifugally passed;and a circumferential receiving receptacle containing a quenching mediumpositioned radially outward from, concentric with and below theperipheral outlet of said sinuous passage so as to be in a position tocatch the exiting spheroidal configurations from the outlet.

2. The apparatus of claim 1 wherein the circumferential receptacle isfilled with a quenching material selected from a group consisting ofwater, oil, liquid salt, liquid silicon, liquid glass and mixturesthereof in any and all proportions.

3. The apparatus of claim 1 wherein the conical shaped projection at thecenter of the anvil is replacable.

4. The apparatus of claim 1 wherein at least one of the surfaces of thesinuous passage is made from at least one material selected from a groupconsisting of graphite. alumina, magnesia, and cast-iron.

5. The apparatus of claim 1 wherein the peripheral outlet of the sinuouspassage is downwardly directed.

6. The apparatus of claim 1 wherein the opening of the inlet sinuouspassage is adjustable.

1! i l t I

1. An apparatus for disintegrating molten liquids into somewhatspheroidal to spherical configuations comprising a rotatable circulardrum having a centrally located opening through which the liquid canflow; a power driven rotatable circular anvil concentric with andlocated below said drum; said drum and said anvil being rotatable inopposite directions; said anvil having a conically shaped centerprojection directly under the opening in the drum and a curvilinearupper surface extending radially outward from said projection whichmates with and is spaced apart from a similar curvilinear lower surfaceon said drum; said curvilinear surfaces forming a sinuous passage havingat least one peak through which the liquid can be centrifugally passed;and a circumferential receiving receptacle containing a quenching mediumpositioned radially outward from, concentric with and below theperipheral outlet of said sinuous passage so as to be in a position tocatch the exiting spheroidal configurations from the outlet.
 2. Theapparatus of claim 1 wherein the circumferential receptacle is filledwith a quenching material selected from a group consisting of water,oil, liquid salt, liquid silicon, liquid glass and mixtures thereof inany and all proportions.
 3. The apparatus of claim 1 wherein the conicalshaped projection at the center of the anvil is replacable.
 4. Theapparatus of claim 1 wherein at least one of the surfaces of the sinuouspassage is made from at least one material selected from a groupconsisting of graphite, alumina, magnesia, and cast-iron.
 5. Theapparatus of claim 1 wherein the peripheral outlet of the sinuouspassage is downwardly directed.
 6. The apparatuS of claim 1 wherein theopening of the inlet sinuous passage is adjustable.